This invention relates to a method of, and apparatus for, winning mineral material such as coal from the pillars left by the bord-and-pillar mining process.
The bord-and-pillar process entails driving a series of stalls into a seam, the stalls defining two sets of parallel passageways at right-angles to one another. Obviously, the process leaves a series of pillars, the pillars being effective to support the roof of the working. Originally, the stalls were won by hand, but nowadays automatic winning machines are used to win the mineral material, particularly coal. However, whichever method of winning has been used, the pillars remaining contain approximately 40% to 70% of the mineral material originally available for winning. It is, therefore, desirable to find a method suitable for winning mineral material from these pillars. Unfortunately, until now, no suitable method has been found for winning the pillars economically, whilst ensuring that the roof of the working is reliably supported during the pillar winning operation. Consequently, using known methods, only part of the pillars can be won, it being necessary to leave substantial portions of the pillars so as to support the roof of the working.
The aim of the invention is to provide a method of, and apparatus for, winning such pillars completely and economically, whilst reliably supporting the roof of the working.